Gear and shaft assemblies come in various configurations. For example, planetary gear sets, typically include a sun gear, a ring gear, a pinion carrier, and at least one pinion (also known as a planet gear). A simple planetary gear set may have one pinion rotatably mounted to the pinion carrier, while a compound planetary gear set may have a plurality of pinions rotatably mounted to the pinion carrier. Each pinion is rotatably mounted to the pinion carrier through a pinion shaft coupled to the pinion carrier. The pinion carrier may revolve around the sun gear's axis of rotation or may be stationary.
Planetary gear sets are typically part of a larger mechanical assembly, such as a transmission for a work vehicle. Planetary gear sets allow for adjustment of the speed and torque of an output shaft by adjusting a gear ratio between an input shaft and the output shaft. This may be accomplished by locking one of the gears, such that it is stationary with respect to a shaft it is rotatably mounted to, or by selecting a second set of gears in a stacked planetary gear set. For example, the sun gear may be held stationary, while the pinion and ring gear are allowed to rotate, the pinion may be held stationary, allowing the sun and ring gears to rotate, or the ring gear may be held stationary, allowing the sun gear and pinion to rotate. Each combination of rotating and stationary gears results in a different gear ratio between the input and output shafts. Alternatively, by locking two gears (such as the sun and ring gears, the ring gear and the pinion, or the pinion and the sun gear) will cause the entire planetary gear set to rotate together. This results in the rotational speed of the input and output shafts being equal.
A common problem in planetary gear assemblies is how to cost effectively supply lubricating fluid to the gears and gear bearings. In some applications, splash lubrication can be utilized. However, in high-performance, long-life applications, it may be desired that lubrication be provided under pressure to ensure that lubricating fluid is provided to the bearing at all times. An additional problem exists in developing such a system that is also low-profile and compact.